Some geolocation techniques in existence use a plurality of satellite or airborne platforms to make respective frequency difference of arrival (FDOA) measurements on a signal received from a transmitter located at an unknown location on earth. The location of the transmitter is determined based on the FDOA measurements. Although the accuracy of a frequency measurement increases with signal duration for signals of a fixed frequency, the situation is more complicated when the signal frequency changes due to oscillator drift and doppler changes. In this case, the FOA (frequency of arrival) at some point in the signal must be estimated from the frequency profile near the point.
It is therefore desirable to provide for geolocation techniques that accommodate signal frequency changes more readily than conventional FDOA techniques.